In the steel industry, the Basic Oxygen Furnace (BOF) is the primary steelmaking vessel in a steel mill. A general goal in the industry is to improve quality control while also reducing production time and cost. However, a common impedance to being able to achieve that goal is the inability to determine, in real time, the temperature of the molten steel bath inside a BOF. As a result of lacking real time, accurate temperature data, target temperatures and chemistries are often missed. Failure to achieve the target temperatures and chemistries during the metal melting process can result in inefficiencies and may even result in having to reinitiate the heating process, resulting in significant economic impact. This lack of ability to determine temperature in real time results in a lack of efficiency that not only applies to BOF's in the steel industry, but also to electric arc furnaces (EAF's) and induction furnaces.
A BOF operates at very high temperatures. As a result, using temperature sensors inside the BOF to take temperature readings is not typically feasible. Furthermore, to the extent that using temperature sensors inside the BOF has been attempted, the high temperatures at which the BOF operates tend to substantially impact the life of the sensors.
There are a few temperature measuring approaches that have been attempted in the industry and have resulted in at least some measure of success. These approaches include the following: using a bomb thermocouple (i.e., temperature sensor); using a spring loaded thermocouple disposed in the tip of a lance; using an infrared camera to sense the temperature of the tip of a lance or the bath itself; and using a thermocouple installed in a tuyere (i.e., a nozzle which is used to blow oxygen into the molten bath in the BOF). While these approaches do provide for the measurement of temperature, the measurements that are taken are basically just a snapshot—a single temperature measurement taken at a specific point in time. Because the temperature of the molten metal bath in a BOF varies greatly with stratification of the level (height) of the bath and proximity to the heating element, none of these approaches effectively provide accurate temperature data with regard to the overall bath inside the BOF.